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Article

Complex Electrical Conductivity of Biotite and Muscovite Micas at Elevated Temperatures: A Comparative Study

1
Institute of Physics of the Earth’s Interior and Geohazards, Hellenic Mediterranean University Research Center, 73100 Chania, Greece
2
Laboratory of Inorganic and Organic Geochemistry and Organic Petrography, Department of Mineral Resources Engineering, Technical University of Crete, 73100 Chania, Greece
3
Department of Geophysics-Geothermics, Faculty of Geology and Geoenvironment, National and Kapodistrian University of Athens, 15772 Athens, Greece
*
Author to whom correspondence should be addressed.
Materials 2020, 13(16), 3513; https://doi.org/10.3390/ma13163513
Received: 12 July 2020 / Revised: 1 August 2020 / Accepted: 4 August 2020 / Published: 9 August 2020
(This article belongs to the Special Issue Electrical and Mechanical Properties of Geomaterials)
The unique physicochemical, electrical, mechanical, and thermal properties of micas make them suitable for a wide range of industrial applications, and thus, the interest for these kind of hydrous aluminosilicate minerals is still persistent, not only from a practical but also from a scientific point of view. In the present work, complex impedance spectroscopy measurements were carried out in muscovite and biotite micas, perpendicular to their cleavage planes, over a broad range of frequencies (10−2 Hz to 106 Hz) and temperatures (473–1173 K) that have not been measured so far. Different formalisms of data representation were used, namely, Cole-Cole plots of complex impedance, complex electrical conductivity and electric modulus to analyze the electrical behavior of micas and the electrical signatures of the dehydration/dehydroxylation processes. Our results suggest that ac-conductivity is affected by the structural hydroxyls and the different concentrations of transition metals (Fe, Ti and Mg) in biotite and muscovite micas. The estimated activation energies, i.e., 0.33–0.83 eV for biotite and 0.69–1.92 eV for muscovite, were attributed to proton and small polaron conduction, due to the bound water and different oxidation states of Fe. View Full-Text
Keywords: mica; biotite; muscovite; impedance spectroscopy; electrical conductivity; electric modulus; high temperature mica; biotite; muscovite; impedance spectroscopy; electrical conductivity; electric modulus; high temperature
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MDPI and ACS Style

Saltas, V.; Pentari, D.; Vallianatos, F. Complex Electrical Conductivity of Biotite and Muscovite Micas at Elevated Temperatures: A Comparative Study. Materials 2020, 13, 3513. https://doi.org/10.3390/ma13163513

AMA Style

Saltas V, Pentari D, Vallianatos F. Complex Electrical Conductivity of Biotite and Muscovite Micas at Elevated Temperatures: A Comparative Study. Materials. 2020; 13(16):3513. https://doi.org/10.3390/ma13163513

Chicago/Turabian Style

Saltas, Vassilios, Despoina Pentari, and Filippos Vallianatos. 2020. "Complex Electrical Conductivity of Biotite and Muscovite Micas at Elevated Temperatures: A Comparative Study" Materials 13, no. 16: 3513. https://doi.org/10.3390/ma13163513

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